The voice is an instrument which the artist must learn to use
with suppleness and sureness, as if it were a limb.
Sarah Bernhardt
Speech is the voice of the heart.
Chinese Proverb
• Resonant means literally to sound again. This
implies that there is a sound to resound. In voice this
sound is phonation created at the larynx through the
oscillating vocal folds.
• Resonance is the “…quality or state of being
resonant.” and the “…ringing quality of an instrument
or voice.” [Encarta World English Dictionary]. What
about resonance creates this “ringing quality” in the
voice? In order to answer that question we need to
examine sound.
• Sound is defined by Daniloff, Shuckers and
Feth as “…a disturbance travelling through
an elastic medium” elastic meaning having
an ability to vibrate.
• Sound can be subdivided into simple and
complex tones.
• Simple tones consist of one frequency, or
cycles of vibration per second.
A simple
sound consists
of one wave
• The second type of sound is called a
complex tone. It is the sum of multiple
simple tones/waves.
• Sound can also be periodic, having a
repeatable wave pattern, like a note on a
• And aperiodic, having a non-repeating
wave pattern, like a metal plate hitting the
• All sound resonates. Place a vibrating tuning
fork against the body of a violin and the violin
will resonate that note. When the violin is
sung into, several notes will be resounded.
Which begs the question, what is about the
nature of a violin that allows resonance?
• As stated above resonance is reaction to sound;
that is, a resonator does not initiate the sound but
responds to it. Sound is vibration and vibration is
• Anything that can vibrate, vibrates at natural
frequencies; when the energies of an initial sound
match the object’s natural frequencies, the object’s
material vibrates in sympathy.
• In addition, if the object contains a cavity of air,
that air will vibrate at frequencies based on its size
and shape. This air filled cavity is known as an
acoustic resonator.
When we feel the vibrations of the
violin tactilely, we are feeling the
resonant quality of its material, its
natural frequencies, but what we
hear is the acoustic resonant
quality of the air vibrating inside
it, its acoustic resonator.
Vocal Tract
• The vocal tract has material (tissue) and air
filled cavities, (pharyngeal, oral and nasal)
that resonate.
• These resonators are excited into vibration
by phonation. So voice is a product of the
larynx (source) resonated by the vocal tract
(transfer function).
Vocal Tract and
Phonation is a complex tone, it is
made up of a fundamental
frequency or Fo (the number of
times the folds open and close per
second-CPS) and harmonic
multiples of the Fo (two times the
Fo, three times, four times etc.)
that fall in intensity (volume) in
an inverse relationship as the
harmonics rise in frequency
(pitch); or as the pitch rises the
volume falls.
• Picture a seesaw; one seat is pitch the other volume, when one
seat is up the other is down. Now picture a whole row of seesaws where the first see-saw’s (Fo) pitch seat is on the ground,
and the last one, its volume seat on the ground; in-between, the
pitch seats rise and the volume seats lower in evenly spaced
steps like a set of stairs.
• Resonators bend the volume seats louder. They don’t affect
pitch, but amplify it by adding their vibration to the source
vibration. If the resonator amplified all notes equally the shape
would change in volume equally for each seesaw. But
resonators do not uniformly resound all vibration; they do so
only near their natural frequencies. In this playground picture,
the pitch sides remain the same, but the volume sides rise
selectively only when they match or are near the natural
frequencies. So the vocal tract bends the seesaws of
harmonics louder.
• The human vocal tract is an open-ended tube, and the resonant
qualities of a tube can be predicted if its size is known.
• Daniloff, Shuckers and Firth write, that depending on the length
of the tube “…energies build in the tube at certain select
resonant frequencies of vibration” [pg. 15, 1980] and they further
state that if you know the length of the open-ended tube you can
predict these frequencies.
• These natural frequencies in voice are termed formants.
• Where the materials and cavities of the vocal tract amplify the
frequencies of phonation are the formants
• Bunch cites Ladefoged’s definition of formants as:
• The peaks in the spectrum of vowels correspond to the basic
frequencies of the vibration of air in the vocal tract. The region
of the spectrum in which the frequency corresponds are
relatively large and known as formants. The formants of a
sound are those aspects of it which are directly dependant on
the shape of the vocal tract, and are largely responsible for the
characteristic quality…it is the presence of formants that
enables us to recognize the different vowels which are
associated with the different positions of the vocal organ.
[Dynamics of the Singing Voice, pg.15, 1997]
Formants change with and depend on different articulatory settings.
Because the vocal tract is different in each of us and able to change
shape, the formants are ever shifting. Longer tubes resonate at lower
frequencies and the opposite is true, different configurations, resulting
tensions and shapes create constrictions that change energies.
Phonation Frequencies for /i:/
136 cps
40th overtone
5440 cps
Fundamental Frequency Plus Vocal Tract
for /i:/ (vocal transfer) Male
Vocal Tract and Resonance
• The dynamic character of the vocal tract allows
potentially infinite degrees of shape. In addition, the
material that defines and shapes the vocal tract has an
affect on the vibration. The relationship between the
resonant material and the air filled acoustic resonator it
surrounds is intimate. Going back to the analogy of the
violin, its material, wood, imparts a quality to its
acoustic resonator. If the violin was made of mink, the
sound would be perceived as less sharp, there would be
less “ringing quality”. The reason for this is that the
mink absorbs sound-the wood reflects it. This is called
Vocal Tract and
When the material’s
sympathetic range is narrow
like wood, the sound tends to
be perceived as bright and
sustaining, if wide like mink,
the sound will be hollow,
build and die quickly. The
more finely tuned the
material surrounding the
cavity, the more desirable
the quality of sound it
• The outcomes of resonance training have been succinctly
termed by Clifford Turner in Voice & Speech in the Theatre:
• In training the resonator our initial aims are:
• 1. Expansion of the cavities in order to impart full sonority to the
• 2. The achievement of balanced resonation, so that no one
cavity predominates to the detriment of the total effect.
• 3. Perfection of the shapes which mould the tone and give it
particular character in the form of the vowels.
The Vocal Tract: Variable
resonators and sound source
Includes all of the air passages above the larynx –
from the glottis to the lips and has three main air
filled cavities (acoustic resonators)
• Oral
• Pharyngeal
• Nasal
Musical Instruments - The remarkable thing about
the human resonator is that it can change shape
• Posterior part of the vocal tract is formed by a tube of muscles known
as the pharynx
Muscles divide into three groups:
– Inferior constrictor muscles
– Middle constrictor muscles
– Superior constrictor muscles
Constriction of these muscles narrows the pharyngeal cavity
Relaxation widens it!
Parts of the pharynx behind the oral, nasal and laryngeal cavities are
– Nasopharynx
– Oropharynx
– Laryngopharynx
Pharyngeal Muscles
• Thin muscles that wrap around the sides and back
wall of the pharynx:
• Superior Constrictor Muscle
– Most complex and the weakest
– Wraps around the upper pharynx, almost reaching the base of the
• Middle Constrictor Muscle
– Overlapped by the Inferior constrictor, it attaches to the horns of
the hyoid bone
• Inferior Constrictor Muscle
– Lowest and strongest
– Arises from both sides of the Thyroid cartilage
The superior, middle
and inferior
constrictors rest
within one another
like flower pots.
Nasal Cavity
• Functions in speech only as a resonator.
– Resonance
• Too much (Hyper-Rhino or Hyper-Nasal)
• Too little (Hypo-Rhino or Hypo-Nasal)
Oral Cavity
Soft Palate – Velum
– Elevators
– Depressors
– Tensors
Hard Palate
Soft Palate (Velum)
• Flexible muscular flap forms the hard palate
• Muscles determine the velum’s position and
thereby how voice escapes and sounds
– Depressors (open the airway to the nose)
– Elevators (close the airway to the nose)
– Tensors (stretch the Velum)
•1. Tensor Palati
•2. Levator Palati
•3. Palatoglossus
•4. Palatopharyngeus
• 5. Superior Constrictor
Oral Cavity
• Hard Palate
• Bounces sound
• Jaw/Tongue/Lips
• Shape the Oral Cavity
• Changes the Formants
• When we come on to voice we vibrate
• Body-the materials of our body vibrate in sympathy to
phonation (natural frequencies)
• Bones/muscles/cartilages/membranes
• Air-the materials of our body surround air-filled
cavities that also vibrate (acoustic resonators)
• Pharynx/mouth/nose
• The relationship between the two is a dance of body
and breath.
• All beauty, resonance, integrity,
Exist by deprivation or logic
Of strange position.
John Ashbery